“What may surprise many people is that we found that the strongest impacts of all were snails controlling seaweeds on rocky shores,” said Alistair Poore, associate professor at the University of New South Wales Evolution & Ecology Research Centre, who led the international study.

“Icons like the Great Barrier Reef would look very different otherwise: the corals and rocks are usually free of seaweed, but that’s only because animals eat all the plants as soon as they grow,” Poore was quoted as saying in the journal Ecology Letters.

The study team analysed results from over 600 experiments, conducted over the past 40 years worldwide, where ecologists have experimentally removed herbivores to understand their importance in structuring marine habitats, according to a university statement.

Manipulating animals in their natural habitats is the most powerful technique to understand how ecological interactions work, they noted.